Good to be back!

[Michael de Sosa <ofsosa@uclink4.berkeley.edu>]

Hello listmembers!

You probably don't remember me, but I was also a member of this esteemed

list, back in the day.  Anyway, my name is Michael (Mike is fine with
me) de Sosa, and I am an undergraduate student at Berkeley.  But that's
all down there in my signature, so I'll get on with the moderately
important stuff now:

Has there ever been a major biogeographic study done for the Mesozoic
Period?  With lists and comparisons of flora and fauna and other such
nitty-gritty details?

My interest arises from an article I ran across while perusing an old
issue of The Canadian Journal of Earth Sciences (I was looking for the
description of Alxasaurus).  Here is the reference:

Russell, 1993.  The role of Central Asia in dinosaurian biogeography.
Can. J. Earth Sci. (30: 2002-2012).

It makes some conclusions about paleogeography based on dinosaurian
distribution on the different continents.  Later, I saw the same theory
in The Dinosaur Encyclopedia, so I guess there haven't been too many
problems with it.  In brief the article says that 1) Central Asia was
isolated for most of the Mesozoic, as shown by an endemic dinosaur fauna

(euhelopodids, sinraptorids, etc.), from the Early Jurassic to the
Aptian-Albian.
2) North America did not separate from Gondwanaland until the Late
Jurassic, shown by nearly identical dinosaurs in the Morrison,
Tendaguru, and South America at that time.
3) Laurasia did not truly form until Aptian-Albian times, when
Euroamerican dinosaurs (iguanodonts, dromaeosaurs) invade Asia.  Asian
dinosaurs migrated to America (tyrannosaurs, ceratopsians) in the Late
Cretaceous.

However (you knew that was coming), this directly contradicts my Geology

textbook.  My geo prof seemed pretty surprised when I asked him about
it, too.  According to what I have learned in his class, Laurasia (a
Euro-Asian-American supercontinent) split off from Gondwanaland (S.
America-Africa-India-Australia-Antarctica) by 180 mya, which is 30-40 my

earlier than predicted by Russell.  This is based on evidence from plate

tectonics.

I want to know if this biogeographic picture is supported by flora and
fauna other than dinosaurs.  Russell briefly mentions Asian mammals -
something to the effect of "Oh yeah, there were these endemic mammals
too."

Thank you in advance.  I look forward to an enlightenment.

--
Michael A. de Sosa
Undergraduate Student
University of California - Berkeley
ofsosa@uclink4.berkeley.edu

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